Classification of a person, e.g., whether a person is an employee, a visitor, an authorized person, an unauthorized person, etc., may be important for a number of applications, including advertising, security, etc. With regard to a professional office building, government office, etc., it may be desirable to distinguish a visitor from an employee to improve security. In this case, both types of users may be present in the same general area, at a same or overlapping time.